In this article, we present a bridgeless hybrid-mode Zeta inverter for distributed energy systems. We integrate the secondary diode of the conventional unfolding-type Zeta inverter into one of diagonal pairs of the secondary-side switches in a bridgeless Zeta inverter. This structure decreases the number of active power components and provides naturally well distributed loss at the body diodes of the secondary-side switches over one cycle of grid voltage, and as a result, increases both output power transfer and reliability. To attain medium-high power capacity with appropriate size of magnetic components, the bridgeless Zeta inverter operates in both discontinuous conduction mode (DCM) and continuous conduction mode (CCM). However, control of the proposed inverter is difficult because of the distinct system dynamics caused by the operations in DCM and CCM. To deal with this control problem, we first identify the mode boundaries and, corresponding to each mode, develop a dynamic model to design a controller. Then, we propose to use a feedback controller plus a feedforward controller supplemented with a repetitive controller that uses a phase-lead compensator. Experimental results using a 300-W prototype demonstrate the feasibility and effectiveness of the proposed modeling and control approach.

中文翻译：

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基于 Zeta 的无桥混合模式逆变器：动态建模和控制


在本文中，我们提出了一种用于分布式能源系统的无桥混合模式 Zeta 逆变器。我们将传统展开式 Zeta 逆变器的次级二极管集成到无桥 Zeta 逆变器中的一对对角次级侧开关中。这种结构减少了有源功率组件的数量，并在电网电压的一个周期内，在次级侧开关的体二极管处提供自然良好的分布损耗，从而提高了输出功率传输和可靠性。为了通过适当尺寸的磁性元件获得中高功率容量，无桥 Zeta 逆变器在不连续导通模式 (DCM) 和连续导通模式 (CCM) 下运行。然而，由于 DCM 和 CCM 中的操作引起不同的系统动态，因此所提出的逆变器的控制很困难。为了处理这个控制问题，我们首先确定模式边界，并对应于每个模式，开发动态模型来设计控制器。然后，我们建议使用反馈控制器加前馈控制器，并辅以使用相位超前补偿器的重复控制器。使用 300W 原型的实验结果证明了所提出的建模和控制方法的可行性和有效性。